Highly efficient solar driven cogeneration of freshwater and electricity

Abstract

The integration of solar steam generation (SSG) and hydrovoltaic effect provides an ideal strategy for solving the water and energy shortage crisis. However, it is still a challenge to collect freshwater while producing electricity at high efficiency. Here, we report the development of a solar driven freshwater-electricity cogeneration (SFEG) device based on a porous hydrophilic graphene aerogel (HGA). Under 1 sun irradiation, the SFEG device in deionized (DI) water exhibited an evaporation rate of 2.17 kg m⁻² h⁻¹ and an output voltage of 0.49 V. Moreover, we reveal that the output voltage and short-circuit current increase first and then decrease as salinity increases. When the salinity is 3.5%, the output voltage reaches 0.87 V with a maximum output power density of 6.84 μW cm⁻², while the evaporation rate maintains 2.01 kg m⁻² h⁻¹. Both the performances of water evaporation and electricity generation are very competitive compared to the state-of-the-art levels. The outdoor experiment demonstrates that the SFEG device can effectively work under real solar irradiation with good durability, suggesting great potential in practical applications.